a. Field of the Invention
The present invention pertains to a ski structure, and more particularly, it relates to an improved ski structure having at least one elastic, tough, box-like inner core frame extending longitudinally of the ski for the major length thereof.
B. Description of the Prior Art
It is generally appreciated that recent improvement in skiing techniques and increase in speed which can be achieved is related greatly to the construction of the skis used. As is well known, a ski has core means which, in olden days, was made of wood but for some time the core means has come to be made with plastic materials for the purpose of uniformity in the quality of the materials of skis and also for producing skis having a good balance as a whole. Thus, it has become possible to provide skis of good quality while meeting the demands of modern skiing in general. Moreover, it is known to mold plastic core means to include a hollow region or internal space therein for reducing the physical weight of skis for improving the controllability or operability of skis.
However, hollow skis still present many problems to be solved and characteristics to be improved. Hollow skis, indeed, do have the advantageous features that they are very flexible and easily adapt themselves to changes in the snow surface condition to exert good snow holding. On the other hand, however, they tend to cause skiers a sort of listlessness due to the absence of weight sensed by the feet of the user because of the actual light weight of such skis. Moreover, during movement, such skis cause the user to sense vibrations. Furthermore, though not of primary significance skis of this type lack a luxurious sensation when touched by the fingers of the user.
Additionally, there have been proposed and placed on the market skis whose core means employs honeycomb materials. Skis of this type have various advantageous features such that they have good twistability and are elastic, they can adapt themselves to the changes in the snow surface condition, and they can absorb impacts and vibrations. However, the honeycomb materials used are made of light aluminum alloys which are very expensive to manufacture and this fact can be termed to be the greatest drawback of the skis of this type. Furthermore, currently known skis having only honeycomb material as their filling members give the user a sensation that the skis are of poor substance and are "weak-kneed" skis.
Still further, skis having a markedly enlarged hollow region, and accordingly having a small thickness around this hollow region in order to minimize the total weight of the skis tend to develop sagging of the upper surface of the skis (as shown in FIG. 7) due to the molding pressure received during the manufacture. This causes to develop between the upper surface and the core members. As a result, the bonding relationship between the component members is destroyed, causing warping during use over an extended period of time.